The Sewol ferry has been safely placed onto a semisubmersible ship that will be used to transport it to the port of Mokpo on South Korea's southwestern coast, finishing one of the most delicate operations of the recovery project, the government said Saturday.

"The vessel was successfully loaded onto the semisubmersible ship as of 4:10 a.m." said the Ministry of Oceans and Fisheries.

Salvage operators will now untie the ferry from the two barges that raised the Sewol from the water where it sank.

Over the next two or three days the hull of the Sewol will be tightly fixed to the semisubmersible ship, which can carry a boat weighing up to 70,000 tons on its deck, before heading to Mokpo, some 87 kilometers to the east. It will take one day to reach port.

Placing the ferry on the transport ship was one of the most complicated and difficult procedures of the salvage operation, as it is largely affected by the weather and tidal currents.

It was difficult to steer the 145-meter-long, 6,825-ton vessel accompanied by two barges onto the wide floating deck of the semisubmersible ship. Authorities had originally planned to finish the process before midnight Friday when the neap tide period ended.

The sunken ferry Sewol is moved onto the semisubmersible ship on March 24, 2017. (Yonhap)

It took more than seven hours for the Sewol to make the 3-kilometer journey up from where it sank to the rendezvous area after the upper part of the hull was raised some 13 meters out of the sea at 11:10 a.m. Friday.

The journey took longer than expected as it took time to change the direction of the three boats -- the Sewol and two accompanying barges -- in accordance with the sea currents before moving toward the semisubmersible ship.

It was a delicate task, as the balance of the ropes linking them together had to be steadily maintained, authorities said.

The raising of the ship had also been delayed for nearly a day as the left rear ramp of the ferry had been hanging down under water and hindering the recovery operation. The procedure resumed after divers cut off all four hinges of the left rear ramp early Friday.

After the ferry safely left the accident site, known for its fast current, the ministry said divers will search carefully for any remains left in the water and on the sea floor. Authorities said underwater fences surrounding the area where the Sewol sank have been set up.

Efforts to raise the Sewol, lying about 40 meters under water, began Wednesday, some three years after it capsized off the southwestern coast of the peninsula near the island of Jindo while en route to the resort island of Jeju on April 16, 2014.

Its sinking, the worst maritime disaster in the country's history, left 304 people dead, including nine still missing.

Earlier, the Seoul government decided to pull the ferry out of the water intact in order to protect any remains of people still missing from the tragic sinking and conduct a detailed investigation into the disaster.

The 85.1 billion won (US$72 million) project to recover the ship is being conducted by a Chinese consortium led by state-run Shanghai Salvage.

A dry dock at the port of Mokpo where the Sewol will be placed after being moved from the sinking site. (Yonhap)

The ministry had originally expected the Sewol ferry to be on land by April 4 or 5.

If the transport process goes smoothly, the ship could arrive at the Mokpo port by the end of this month.

A total of 304 people, most of whom were high school students on a school trip, died when the ferry sank on April 16, 2014, with investigators concluding that the sinking was a man-made disaster. Nine bodies are still unaccounted for. (Yonhap)